SUMMARY

Various fuel cycles for a sodium cooled, subcritical, fast reactor with a fusion neutron source for the transmutation of light water reactor spent fuel have been analyzed. All fuel cycles were 4-batch, and all but one were constrained by a total fuel residence time consistent with a 200 dpa clad and structure materials damage limit. The objective of this study was to achieve greater than 90% burn up of the transuranics from the spent fuel. The first two fuel cycle scenarios (A and B) examined the difference between in-to-out and out-to-in fuel shuffling for once-through fuel cycles, and the third scenario (C ) examined the effect of a design variation on power flattening. The fourth fuel cycle (D) examined the achievement of greater than 90% TRU burnup in a once-through fuel cycle, assuming the development of an advanced structural material that could withstand the associated radiation damage. Finally, the fifth fuel cycle (E) analysis, which is representative of the reference fuel cycle envisioned for advanced burner reactors (ABRs), examined the achievement of 90% TRU burnup by repeated reprocessing/recyling of the TRU fuel. The reference fuel cycle, in which the TRU fuel was reprocessed, mixed with fresh TRU fuel, and recycled into the reactor after each 24% burnup residence time, achieved greater than 90% TRU burnup after 9 residence times. The fuel ultimately discharged to the high level waste repository (HLWR) was reduced relative to the original spent nuclear fuel (SNF) from which it was produced by 99% in integral decay heat at 100,000 years after discharge. The resulting repository volume required for the millennial storage of the fuel discharged from the SABR was calculated to be 1/130 the volume that would have been required to store the original SNF from which that fuel was made.